Yarn brake of the sling type

ABSTRACT

A yarn brake of the sling type comprising a pair of yarn guides each having yarn guide formations. One of the yarn guides is movable and biased for movement away from the other by suitable means such as a coil mechanically coupled to the guide, to which coil direct current is applied and which is suspended in a magnetic field. A second coil in a magnetic field is mechanically coupled to the movable yarn guide for generating a voltage according to the velocity of movement of the guide. The voltage can be applied to a detector which in turn signals undesirably large fluctuations or movements in the guide.

United States Patent [72] Inventor Geert J. Vermeulen Deurne, Netherlands [211 App]. No. 748,341 [22] Filed July 29, 1968 [45] Patented May 11, 1971 [73] Assignee N. V. Machinefabriek L. te Strake Deurne, Netherlands [32] Priority Sept. 12, 1967 [33] Netherlands [3 l 67 12482 [54] YARN BRAKE OF THE SLlNG TYPE 6 Claims, 2 Drawing Figs.

[52] US. Cl 242/36, 242/ l 54 [51 Int. Cl B65h 63/00, B65h 59/26 [50] Field of Search 242/154, 153, 147, l49,45, 36, 37

[56] References Cited UNITED STATES PATENTS 2,222,847 1 H1940 Kent 242/37 Primary Examiner-Stanley N. Gilr'eath Attorney-Christel & Bean ABSTRACT: A yarn brake of the sling type comprising a pair of yarn guides each having yarn guide formations. One of the yarn ides is movable and biased for movement away from the 0 er by suitable means such as a coil mechanically cou pled to the guide, to which coil direct current is applied and which is suspended in a magnetic field. A second coil in a magnetic field is mechanically coupled to the movable yarn guide for generating a voltage according to the velocity of movement of the guide. The voltage can be applied to a detector which in turn signals undesirably large fluctuations or movements in the guide.

Patented May 11 1971 DETECTOR INVENTOR.

GEERT JAN VERMEULEN A AT'I'O RN EYS YARN BRAKE or THE SLING TYPE The invention relates to a yarn brake of the sling type, with a first yarn guide with pins or eyelets, which is movable with respect to a second yarn guide with pins or eyelets and which is subjected to such a setting force, that it tends to move away from the second yarn guide.

Such yarn brakes usually are used on warping equipment for providing a constant tensile force at the output end of the yarn passed through the yarn brake, independent upon fluctuations at the input end which are caused by unwinding cones and the like. Since the warping machine must be stopped as soon as possible when a yarn breakage occurs, the warping machine moreover is usually provided with a plurality of yarn guards, which provide an alarm signal as soon as a yarn breakage occurs.

Since moreover slubs must be removed from the yarns, for which purpose the machine must also be stopped, warping machines further are usually provided with slub detectors, which provide an alarm signal as soon as a slub passes.

The invention aims at providing a yarn brake which can also serve as yarn guard and as slub detector, without requiring the yarn to be passed through separate devices.

For that purpose, a yarn brake of the kind referred to is characterized by a coil in a magnetic field, which is mechanically coupled with the first yarn guide and which generates a voltage which is dependent upon the velocity of movement of the coil.

In a yarn brake of the sling type, variations of the input tensile force of the yarn are compensated by automatically controlled movements of the two yarn guides with respect to one another, whereby the embracing angle of the pins or eyelets varies and consequently the friction experienced by the yarn varies, so that notwithstanding a variable input tensile force, the output tensile force is constant. During normal operation of the yarn brake, the movements of the yarn guides stay within certain limits, whereby the voltage generated in the coil also stays within certain limits.

A soon as the yarn breaks, the input tensile force is removed and the two yarn guides rapidly move away from one another, for keeping the output tensile force as constant as possible. This violent movement generates a much stronger output voltage in the coil than during normal operation, and this output voltage can cause a detector connected to the coil to respond and to supply an alarm signal.

If an unusually violent variation of the input tensile force of the yarn occurs due to incorrect unwinding of the yarn or other causes, the yarn guide movements are also unusually violent and the coil generates a larger output voltage than during normal operation, which can also cause a detector connected to the coil to respond.

If a slub passes through the yarn brake, the friction experienced by the yarn is temporarily so much larger, that the yarn guides are violently moved towards one another as soon as the slub enters the yarn brake. These unusually violent movements too generate an abnormally high output voltage of the coil, which also causes the detector to respond.

A yarn brake of the sling type is therefor able to execute not only its own inherent function, but can also serve as yam guard and slub detector, provided that the movable yarn guide is coupled mechanically with a coil in a magnetic field.

The invention is further elucidated below with reference to the drawing, which shows in FIGS. 1 and 2 two embodiments of a yarn brake according to the invention.

In FIG. ll, the yarn 1 is passed around the pins 2 of a stationary yarn guide 3 and the pins 4 of a movable yarn guide 5. The movable yarn guide 5 is biased against the force exerted by the yarn 1 by a suitable device, such as a moving coil 6 to which a direct current is applied from the terminals 7 and 8 and which is suspended in a magnetic field. With a view to the operation as yarn guard and slub detector, a moving coil 9 is also coupled with the movable yarn guide 5 and this coil is also suspended in a magnetic field. In the moving coil 9 a voltage is induced which is dependent upon the velocity of movement of the moving coil 9 in the magnetic field and which, therefore, is dependent upon the velocity of movement of the movable yarn guide 5. This output voltage can be obtained between the terminals 8 and 10 and can be applied to a detector which provides an output signal as soon as the peak-to-peak value of the output voltage of the moving coil 9 exceeds a predetermined value. This is the case if due to incorrect unwinding or other causes, the input tensile force of the yarn l fluctuates to an unacceptable degree, whereby the movements of the movable yarn guide 5 are also unacceptably violent.

If the yarn I breaks its tensile force is removed and the movable yarn guide 5 consequently abruptly moves away from the stationary yarn guide 3. This abrupt movement induces a corresponding voltage peak in the moving coil 9 and the detector can be designed so as to provide an output signal if the instantaneous value of the voltage induced in the moving coil 9 exceeds a predetermined limit as a consequence of this voltage peak.

If a slub passes the yarn brake, the movable yarn guide 5 due to the suddenly increasing friction which the yarn experiences, moves abruptly towards the stationary yarn guide 3 and this abrupt movement too induces a corresponding voltage peak in the moving coil 9, which under these circumstances has the opposite polarity, however. The detector connected to the moving coil 9 can be so designed as to provide an output signal if the instantaneous value of the voltage induced in the moving coil exceeds a predetermined value in that direction.

The device for exerting a bias on the movable yarn guide 5 need not necessarily consist of a moving coil 6 and a dif-' ferently designed coil or a mechanical device can also be used for that purpose. If the bias is provided by a coil which is mounted in a magnetic field, it is in fact not necessary to couple a separate moving coil 9 with the movable yarn guide 5 for providing the desired output voltage. It is also possible to use the voltages which the movements induce in the biasing coil 6 proper. For that purpose, and as shown in FIG. 2, these output voltages can be derived from the moving coil 6 through a capacitor 11 and the terminals 8 and 12, in which case the moving coil 9 is superfluous. The capacitor 11 serves for suppressing the voltage which the driving current originating from the terminals 7 and 8 generates in the moving coil 6 and moreover, it increases the differentiating action.

Further, it should be observed that neither the biasing coil nor the detector coil need be designed as a moving coil. Instead, they can also be designed as coils which are so coupled with the movable yarn guide 5, that they move linearly in a magnetic field, or they can be designed as stationary coils which cooperate with a core coupled with the movable yarn guide 5.

lclaim:

I. A yarn brake of the sling type, having a pair of yarn guides each having yarn guide formations, one of said yam guides being movable with respect to the other and means biasing said one yarn guide for movement away from the other, said yarn brake characterized by a coil in a unidirectional magnetic field mechanically coupled for movement with said movable yarn guide, said coil generating a voltage according to the velocity of movement thereof.

2. A yarn brake according to claim 1 wherein the coil is energized to exert a setting force on said one yarn guide.

3. A yarn brake according to claim 1 including a detector connected to said coil to provide a signal when the voltage induced in the coil exceeds a predetermined peak-to-peak value.

- 4. A yarn brake according to claim 2 including a detector connected to said coil to provide a signal when the voltage induced in the coil exceeds a predetermined peak-to-peak value.

5. A yarn brake according to claim 1 including a detector connected to said coil to provide a signal when the instantaneous voltage induced in the coil departs from a predetennined voltage range.

6. A yarn brake according to claim 2 including a detector connected to said coil to provide a signal when the instantaneous voltage induced in the coil departs from a predetermined voltage range. 

1. A yarn brake of the sling type, having a pair of yarn guides each having yarn guide formations, one of said yarn guides being movable with respect to the other and means biasing said one yarn guide for movement away from the other, said yarn brake characterized by a coil in a unidirectional magnetic field mechanically coupled for movement with said movable yarn guide, said coil generating a voltage according to the velocity of movement thereof.
 2. A yarn brake according to claim 1 wherein the coil is energized to exert a setting force on said one yarn guide.
 3. A yarn brake according to claim 1 including a detector connected to said coil to provide a signal when the voltage induced in the coil exceeds a predetermined peak-to-peak value.
 4. A yarn brake according to claim 2 including a detector connected to said coil to provide a signal when the voltage induced in the coil exceeds a predetermined peak-to-peak value.
 5. A yarn brake according to claim 1 including a detector connected to said coil to provide a signal when the instantaneous voltage induced in the coil departs from a predetermined voltage range.
 6. A yarn brake according to claim 2 including a detector connected to said coil to provide a signal when the instantaneous voltage induced in the coil departs from a predetermined voltage range. 